Terminology

Source - original audio stream/video file subtitles are timed for.

Destination - new audio stream that we want to match after shifting.

Event - single subtitle line with its start/end time.

Linked event - event linked to some other event. This event is excluded from search and will later use the shift of the event it's linked to (parent event).

Chapter group - single chapter or automatically detected group, e.g. "opening", "part A", "part B" and so on.

Search group - a number of events grouped together, e.g. 100 lines of fbf typesetting or a single dialogue line.

Typesetting group - search group with more than one event.